Electron distribution between valleys and narrowing of band gap at picosecond superluminescence in GaAs

High-speed optoelectronic effects, caused by interconnection between the picosecond stimulated emission and the kinetic processes in dense hot electron-hole plasma in GaAs, are briefly reviewed. The newest effect of this class is reported in detail. It deals with the band gap narrowing as a result of generation of multi-component plasma in GaAs. The plasma is generated by a picosecond light pulse and the picosecond stimulated emission is observed. In this situation, the total concentration of the pairs of photogenerated electrons and holes is experimentally proved to be the only parameter defining the electron distribution between I₆- and L₆-valleys and the corresponding narrowing of the band gap. This is explained by the fact that in the presence of the emission the temperature and concentration of the charge carriers are approximately bound